The van der pol equation: z',-μ (1-x^2) 2' + x = 0 with x(0) = 0, x'(0) = 1 has been used in models from biology, circuits, and seismology. write this equation as a system of two first order odes. include the initial conditions for the system.

Lance lived in portugal and brazil for a total of 14 months to learn portuguese. he learned an average of 130 new words per month when he lived in portugal, and an average of 150 new words per month when he lived in brazil. in total he learned 1920 new words. write a system of equations to represent the situation. use x to represent portugal, and y to represent brazil

Write the fraction or mixed number and the decimal shown by the model

How many real-number solutions does the equation have? -4x^2 + 10x + 6 = 0 a. no solutions b. two solutions c. infinitely many solutions d. one solution